Solar and wind are the current buzzwords in renewable energy, and DIY articles abound on the internet. Readers who are handy with tools, and who happen to be licensed electricians, may find the suggested projects easy to complete. For the rest of us, installing any kind of interface to the utility power grid is definitely not DIY.

Biodiesel is also a popular topic, and if you grew up around a grandfather or a bunch of uncles who distilled moonshine in the hills of Kentucky, then it may be the perfect option for you. As with solar photovoltaic panels and wind turbines, however, most of us will not fall into this category.

So what's left? Well, not all solar energy projects involve tapping into our home's electric system. In fact, some of the least expensive and most cost-effective projects don't involve wiring at all. Solar heating and solar hot water can be completely passive systems that dramatically cut down on residential energy consumption.

Passive solar technologies use no fans, motors, pumps or moving parts of any kind. They usually make use of sunlight to provide heat, but solar lighting is also an easy DIY project.

The simplest example of solar heating is the installation of insulated windows on the south side of a house. The winter sun is lower in the sky than the summer sun, so sunlight enters south-facing windows and heats the air inside the home. Insulated glass keeps the heated air inside, and the furnace does not need to run as often to keep the home warm.

In the summer months, the goal is to keep heat out of the home. The summer sun travels a higher arc in the sky, and the roof eve will shade a properly positioned window. Another option is to install a blind to block summer sunlight, or to apply a reflective film treatment to the glass for the summer months.

Some homeowners create a thermal mass by using dark colors or by placing heat-retaining objects in the path of the sunlight. For example, a dark-colored cinderblock wall will absorb solar heat, because of its dark color, and radiate the heat back as the sun sets in the evening.

You probably don't want to place a black cinderblock wall inside your home, but similar approaches can be used. Dark-colored paints on walls that receive direct sunshine will absorb and store more heat than light- colored walls. Dark flooring can have the same effect. The key to this approach is that sunlight must strike the surface. Simply having darkly painted walls in a room will otherwise have no effect.

Solar water heating projects are slightly more complex, but they can still easily be tackled as a DIY project, and they use this same principle of retained heat. Here's how they work: A black container is placed on the roof of the home, and the cold water supply is piped into it. Water from the container is used to feed into the cold water supply line for the home's conventional hot water tank.

As the container on the roof absorbs the heat from sunshine, the water inside the container is heated. When hot water is drawn from the hot water tank inside the home, it is resupplied with pre- heated water from the solar water tank instead of cold public water. This causes the conventional hot water heater to cycle less frequently and reduces energy costs for the home.

Hot water tanks use a lot of energy through the year, and solar hot water tanks can have a large impact on a residential energy bill. Of course, the example cited above was just to explain how the process works. In order to be effective, special tanks have to be used. These are typically arrays of large black tubes encased in glass sheathes.

The glass sheathes are evacuated, like long thermos bottles, and the heat absorbed by the black tubes does not easily radiate back out into the air. Solar hot water tanks often heat water sufficiently that the interior conventional hot water tank does very little work at all.

This article was written by the PR division of Solar Panels UK.